This invention relates to an electrical connector which connects a printed circuit board to another printed circuit board, a flexible printed circuit, a liquid crystal display, etc.
A conventional electrical connector will be described referring to FIGS. 1, 2, and 3. The conventional electrical connector is described in Japanese Unexamined Patent Publication (JP-A) No. 102758 of 1999.
A main body 31 of the connector is a generally rectangular parallelepiped-shaped insulator which is molded of resin. The main body 31 has a plurality of grooves 33 formed therein parallel to one another. Thus, each of the grooves is defined by a bottom wall 32, an upper wall 35 confronting the bottom wall 32, and opposite side walls. The upper wall 35 is provided with a plurality of openings 34. The bottom wall 32 is provided with an accommodating space 36 connecting with the groove 33. The side walls are provided with press-fit grooves 37 along the both sides of the groove 33, respectively.
Each of a plurality of contacts 41 are inserted into each of the grooves 33, respectively. Each of the contacts 41 is made of elastic copper alloy to a long plate-shape. Each contact 41 has a base portion 42 and a contact portion 43 narrower than the base portion 42, both of which are connected to each other through a U-shape bent portion 41a. The contact portion 43 can elastically displaced around the bent portion 41a. The contact portion 43 is provided with a projecting portion 43a which is formed by bending the contact portion 43 in the vicinity of a free end of the contact portion 43 into an inverted V-shape. The base portion 42 has a rectangular accommodating hole 42a under the contact portion 43. When the contact portion 43 is downward displaced about the bent portion 41a, it passes through the accommodating hole 42a and is received in the accommodating space 36. Two triangular press-fit projections 42b are formed at both sides of the crosswise direction of the base portion 42, respectively, and are fitted into the press-fit grooves 37, respectively. The base portion 42 is provided with a terminal portion 44 at an end opposite to the bent portion 41a. 
FIG. 1 shows the state that the connector is mounted on the surface of a first printed circuit board 51. The main body 31 is supported on the first printed circuit board 51 and the terminal potion of each of the contacts 41 is connected and fixed to a circuit pattern (not shown) on the first printed circuit board 51. The projecting portion 43a of the contact 41 protrudes by the height h from the upper surface of the confronting wall 35 of the main body 31.
Now, a second printed circuit board 52 to be connected to the first printed circuit board 51 through the connector is disposed at the distance d away from the surface of the first printed circuit board 51, and is in contact with the projecting portion 43a of the contact 41. Then, the second printed circuit board 52 is pushed down to the first printed circuit board 51, the contact portion 43 of the contact 41 deforms elastically from the position shown by the solid line to the position shown by the two dots-chain line in FIG. 1. The second printed circuit board 52 stops at the position when the lower surface thereof has run against the upper surface of the upper wall 35. At this time, a circuit pattern (not shown) of the second printed circuit board 52 connects with the circuit pattern (not shown) of the first printed circuit board 51 by way of a route from the projecting portion 43a of the contact 41, through the contact portion 43, the base portion 42, and the terminal portion 44.
In the conventional connector, a stroke of the projection portion 43 moved by the second printed circuit board 52 pushed down is sufficiently large because of the provision of the accommodating hole 42a and accommodating space 36. At that time, the contact portion 43 is lowered through the accommodating hole 42a below the base portion 42 as shown by the imaginary line and a curvature of the bent portion 41 is therefore increased so that the bent portion 41a may unfortunately be plastically deformed. In order to avoid the undesired plastic deformation of the bent portion 41a, it is desired to increase the width of the bent portion 41a. However, the width of the bent portion 41a is limited as described below. In assembling the conventional electrical connector, the press-fit projections 42b are formed so as to guide the contact 41 press-fitted into the main body 31 of the connector, in cooperation with the press-fit grooves 37 formed in the main body 31. Therefore, the width of the bent portion 41a of the contact 41 cannot be formed with a size greater than an interval between the opposite side walls of the grooves 33 where the press-fit grooves 37 are formed.
Further, since the base portion 42 is provided with the accommodating hole 42a through which the contact portion 43 passes, widths of the base portion 42 and the groove 33 cannot be made so small so that the connector is impossible to be made with a small size as desired.
It is therefore an object of this invention to provide an electrical connector having a plurality of contacts with a compact size wherein the contacts are stably held, and have excellent elasticity with a desired stroke of contact region of the contact portion.
This invention is applicable to an electrical connector having at least one contact held in at least one contact accommodating groove formed in an insulator, the contact accommodating groove defined by a bottom wall, opposite sidewalls, and an end wall and being open upward and at the opposite end, the contact comprising a base portion press-fitted in the contact accommodating groove, a contact portion projecting from the contact accommodating groove upward, and a U-shape spring portion connecting the base portion and the contact portion.
In the electrical connector according to this invention:
the contact accommodating groove comprises a relatively large width section adjacent to the end wall and a relatively small width section adjacent to the open end;
the opposite side walls at the relatively small width section being formed with press-fit grooves adjacent to the bottom wall;
the base portion of the contact being formed with lateral projections laterally projecting from the opposite sides of the base portion, the lateral projections being press-fit in the press-fit grooves respectively; and
the base portion of the contact has a slender part which extends between the U-shape spring portion and the lateral projections and which is smaller in width than the width of the relatively small width section of the contact accommodating groove.
The U-shape spring portion of the contact preferably has a width less than but approximately equal to the width of the relatively large width section of the contact accommodating groove.
The contact portion of the contact preferably has a width smaller than the U-shape spring portion, and the contact portion is slantingly and upward bent at a bent portion apart from the U-shape spring portion and is folded to form a U-shaped folded portion projecting slantingly and upward.
According to another embodiment, the electrical connector has a plurality of the contacts which are accommodated in a plurality of contact accommodating grooves, respectively.
In an embodiment, the plurality of contact accommodating grooves are arranged at both sides of a central partitioning wall and in parallel with each other in each of the sides.
The end wall of each of the plurality of contact accommodating grooves is preferably defined by the partitioning wall.
The partitioning wall preferably has a top end with small flange portions oppositely therefrom to the contact accommodating grooves at both sides of the partitioning wall, the top end and the flange portion forming a flat upper surface.